66 NEW YORK STATE MUSEUM 
quite characteristic of the type. The planes of w:(3145) which modify 
the vertical terminations are in most cases well developed but dull, and gave 
poor reflections. A positive scalenohedron in this zone was noted between 
(1011) and (2131). From several measurements on crystal 2, this scaleno- 
hedron seemed to agree closely with H:(3142) but the form could not be 
established to the writer’s satisfaction and is not included in-the list although, 
for the sake of preserving the crystal habit, it is indicated from these indexes 
on the figure illustrating the type. 
The positive scalenohedron K:(2131) is here developed as a series of 
broad faces of maximum brilliancy supplying excellent points of reference 
in this zone. The positive scalenohedron T:(4371) occurs as a series of 
narrow, striated and somewhat rounded faces lying between (2131) and 
(1120). The form is well established on four of the eight crystals 
measured. 
The positive scalenohedron $: (6281) is here developed to about the 
same extent asin type III. The faces are rough and although the form was 
well established the measurements varied rather more than in the case of 
the previous types. 
A twinned crystal of this type yielded also the negative scalenohedron 
x: (4.16.20.3), the positive scalenohedron 9: (19.10.29.6) and the positive 
rhombohedron” k: (11.0 11.1). @he latter \ two must be regarded as 
doubtful. 
Plate 4, figure 1 represents an average crystal of this habit. The 
stereographic projection, plate 5, figure 1, shows the interesting zonal 
relations between the forms occurring on the four types. 
The distribution of the forms is given in the following table. 
